Three little words; two Government changes of heart; one financial headache for investors.

Capital gains tax (CGT), that slice of profit that you have to pay to Revenue and Customs when cashing in on hefty rises in the value of your assets, has proved nothing but trouble since October 2007.

That month saw Chancellor Alistair Darling detonate a pre-Budget bombshell when he announced the abolition of the old 'tapered' CGT regime that allowed you to whittle your tax rate down to 10 per cent (on gains over the £9,200 tax threshold) if you held on to your assets for long enough.

Instead, Mr Darling proposed a new uniform rate of 18 per cent that, from April this year, would usher in a simpler and more transparent CGT.

Except few in business saw it that way, and no wonder: entrepreneurs suddenly faced an 80 per cent tax rise upon selling their business while those who invested in company 'save as you earn' (SAYE) schemes – swapping a chunk of salary for the chance to buy shares at a hoped-for cheaper future price – were staring at new heavy penalties for commitment to saving.

Now, after four months of wrangling and a wavering Government, the dust looks at last to have settled.

So what does the new landscape look like? First, a major new concession has been given to business owners.

Instead of the flat 18 per cent, there is now a new lower 'lifetime' rate of 10 per cent for gains of up to £1m (provided the proprietor has at least a 5 per cent stake in the company).

This 'lifetime' rate means the serial entrepreneurs can at least sell multiple businesses throughout their career - but the 10 per cent concession on CGT will run out after £1m has been made, at which point the new 18 per cent will kick in.

"After four months of wrangling, the dust looks at last to have settled."

In particular, this last-minute change of heart is set to benefit thousands of older entrepreneurs close to retirement and preparing to sell in order to fund their old age, who would otherwise have faced swingeing tax penalties on their nest egg.

"The new entrepreneurs' relief will be welcomed by many small businesses but might still not be enough for certain serial entrepreneurs who feel that the removal of the effective tax rate of 10 per cent could be a real disincentive," warns Dominic O'Connell, head of tax, trust & estate planning at Coutts.

"Additionally, owners of larger enterprises - often with very significant inherent gains - will obviously be disappointed to see their effective tax rate on gains above the £1m threshold move from 10 to 18 per cent."

Members of employee SAYE schemes will sadly not be spared the more punitive CGT rates from April 6.

According to ifsProShare, a not-for-profit body that encourages share ownership in the workplace, about 43,000 out of 270,000 employees who invest in SAYE schemes are set to make gains in excess of this year's £9,200 CGT limit.

As it stands, if held for two years by higher earners, the gain over this threshold would normally have qualified for full CGT taper relief and seen a huge fall in the tax rate from 40 per cent to 10 per cent. Although there had been hopes that Mr Darling would change his mind, they'll now still have to pay 18 per cent.

The other losers include investors who have held – for two years – shares listed on the Alternative Investment Market (AIM) exchange for burgeoning companies; they will also see their CGT bills rise from 10 to 18 per cent from April.

AIM is a hotbed of young business talent in desperate need of capital injections by investors looking for tax breaks and, again, the Chancellor's refusal to change tack on higher taxes for yet another aspect of entrepreneurialism has won few friends.

"Owners of larger enterprises will obviously be disappointed to see their effective tax rate on gains above the £1m threshold move from 10 to 18 per cent."

The higher CGT penalties have been partly blamed for a recent fall in the AIM index as investors scramble to sell off their shares - and pay less CGT - before the April changes are ushered in. One option for investors holding onto big gains could be to benefit from the lower tax rate by selling ahead of the 6 April deadline, and then buy back their shares.

"It is likely that there will be 'winners' and 'losers' but there are still planning opportunities available, both before and after 6 April," stresses O'Connell. "However, it is imperative to take bespoke professional tax advice."

The few beneficiaries of the new lower CGT regime to remain unscathed by Mr Darling's tinkering include the owners of second homes or buy-to-let portfolios.

Today's rules dictate that, when selling, CGT has to be paid at 40 per cent on profits above your £9,200 allowance or – if you've held the properties for at least ten years – at 24 per cent.

But, from 6 April, owners of both second homes and buy-to-lets can now save thousands of pounds by paying much less tax at the lower 18 per cent – and won't have to wait for years before cashing in either, as there's no time limit.

In particular, the tax benefits are clear for those higher-rate earners who have recently taken a plunge into the buy-to-let market and made a profit by owning a property for less than 36 months.

If they were to sell their buy-to-let today, CGT would have to be paid at 40 per cent. But come April 6, they'll be faced only with a new, lower CGT bill of 18 per cent.

"Although legislation is still in draft format, some are upset by what they see as proposals that effectively favour property owners over entrepreneurs," O'Connell adds.

"However, it shouldn't be forgotten that many buy-to-let owners - particularly those with substantial portfolios – do consider themselves entrepreneurs."

There's one final significant CGT benefit for investors who have shares listed on the London Stock Exchange: the new 18 per cent CGT applies instead of the usual 40 per cent and still beats the minimum CGT rate of 24 per cent for which – again – you would have had to wait for a decade to qualify.

By Sam Dunn